At the back of Ogden Avenue Materials, gravel, sand and recycled bits of asphalt shingles and pavement lie in piles. That’s an advantage of asphalt — it’s 100 percent recyclable. (WBEZ/Katherine Nagasawa)

The raw materials are dumped into a feeder, which deposits them onto the conveyor belt. (WBEZ/Katherine Nagasawa)

The conveyor leads to a metal drum, lower left, where the virgin rock particles are heated. Then, they’re combined with recycled asphalt and a hot petroleum tar called asphalt binder. Asphalt binder is basically the “scrapple” of petroleum — the dense base left over after refineries distill all the other oils needed for products like gasoline, kerosene and jet fuel. (WBEZ/Katherine Nagasawa)

The finished asphalt is stored in six 60-foot-high silos, each of which can hold 250 tons. (WBEZ/Katherine Nagasawa)

Trucks drive underneath the silos and sit on platforms, which are actually giant scales. (WBEZ/Katherine Nagasawa)

Hot asphalt pours out of chutes at the bottom of the silos into the truck beds. It comes out at 300 degrees, so drivers have to be careful -- staying inside with their windows closed. (WBEZ/Katherine Nagasawa)

The whole operation is run out of a control tower. During business hours, the plant runs continuously. (WBEZ/Katherine Nagasawa)

The asphalt is transported to the job site, where it’s spread thin by the paving machine and workers as it’s cooling. It’s driveable within half an hour. (WBEZ/Katherine Nagasawa)